Invisalign is a clear plastic that is elasticated, and it puts pressure to allow the teeth to move into a more desirable position.
The patient wears this on their teeth for one week, and within that one week, it will move all of the teeth that it’s designed to move about 1/4 of one millimeter. So, you go through a sequence of different aligners over some time changing them every week. Then, they slowly move your teeth into a more favorable or attractive position. The appliance is removable, meaning that the patient can take it out and put it back in again anytime.